DE2740505C2 - - Google Patents

Description

The invention relates to recording with high laser beams Intensity and materials particularly suitable for this purpose. The invention is based on a recording material, as stated in the preamble of claim 1 becomes.

J. Micrographics, Vol. 8, No. 6, July (1975), 265-273 a "heat mode" record called high-resolution thermal Laser recording described. By definition the term "heat mode recording" includes any method one by absorbing energy from a laser beam's temperature of the recording medium to a point where tangible physical and / or chemical changes either directly or indirectly through the action of additional forces takes place.

Some non-silver halide materials have been used for heat mode recording found suitable. For example according to the description in US Pat. No. 3,314,073 by vacuum deposition or spraying metallic films obtained imagewise evaporated on the areas hit by the laser radiation.

A suitable one for high intensity laser recording Class of organic materials represent organic coatings  are made up of one or more, in a plastic binder dyes contained exist. Two kinds of Recording materials can be considered here namely those in which a dye is under the influence the radiation directed at it discolors or evaporates, as well as those in which the thermoplastic polymer binder layer is deformed by the thermal energy, which have a high absorption at the laser wavelength. The first type of these materials, which is a very high amount of dye contains, for example, in US-PS 34 65 352. A typical example is a 17% solid solution of a triphenylmethane dye in a cellulose nitrate binder. The second type of material is in the US PS 34 75 760. Examples of these materials are thermoplastic binder layers based on Vinyl toluene butadiene, polystyrene terphenyl, polyethylene or cellulose nitrate in a mixture with, for example, 25% by weight of a nigrosine dye.

An important characteristic of laser heat mode recording is the occurrence of a threshold effect. With others Words, it takes place below a critical intensity, d. H. an energy threshold (watt / cm²) no recording regardless of how long the exposure time is, which means that image stabilization is unnecessary.

Not in the area of "heat mode recording" vesicular films known as KALVAR® Films, make a dry one, for laser recording suitable imaging material. In J. SMPTE 83, 588-599 (July 1974) is a laser recording system using a helium-cadmium laser for writing described on KALVAR® film. The helium-cadmium laser has an output power of about 10 mW and generates  a laser beam of monochromatic light Wavelength 441.6 nm. The KALVAR® film contains photosensitive diazo compounds in one thermoplastic binder, e.g. B. polyvinyl chloride. Minor amounts of Cleave nitrogen from the diazo compound. By Subsequent overall heating expands the nitrogen microscopic bubbles, because of their Refractive index that differs from that of the binder medium, act as light-scattering centers (see for example Jaromir Kosar "Light sensitive Systems" - John Wiley & Sons, Inc. New York (1965), pp. 276-277).

The photosensitive KALVAR film, e.g. B. KALVAR MIKROLITH 1000® film, which is not a heat mode recording film is normal in an office Illumination before or after imagewise exposure only can be handled safely for a few minutes. After imagewise exposure, the film must be heat-developed However, before the exposure, no essential Exposed to temperatures above 32 ° C.

Vesicular images can also be made into a film material by photodepolymerization are generated from polyketones, which from low-boiling monomers formed according to US-PS 30 91 532 will.

The latent image from the monomer is obtained by heating the Material to a temperature of about 120 to over 160 ° C. developed to form a vesicular image.  

Another proposed for vesicular imaging Images are described and existed in US-PS 31 83 091 essentially from a compound, e.g. B. polyvinylidene chloride, those when exposed to actinic hydrogen halide which splits into a reaction with a gas-forming compound, e.g. B. an alkali or alkaline earth carbonate, hydrogen carbonate, oxalate or tartrate occurs. A Recording material of this type is used for the development of a visible vesicular image after development for 30 sec Heated to 130 ° C.

The invention has for its object a recording material for the direct generation of a light-scattering image by means of a Develop laser beam, the material at least one thermoplastic polymer layer with at least one dye contains.

Another task is the development of a process for direct generation of a light-scattering image in at least one a recording layer containing a thermoplastic polymer by means of a laser beam.

The material of the invention should have the advantage, not in the Darkroom needs to be handled against the highest intensities occurring on earth from non-focused Sunlight insensitive should be as unlimited as possible Storage stability both before and after the stage of Have imaging and should after a previous recording process for recording another amount of information sensitive to the information already stored be.

The objects on which the invention is based are achieved with a recording material of the aforementioned type, in which the dye has good photochemical stability, the dye of the layer has an optical density in directional light of at least 0.1, based on a monochromatic wave one of which (s) absorbed laser beam, gives the dye in an amount of at most 10 wt .-%, based on the thermoplastic polymer (s) of this layer, in which the polymer layer as a thermoplastic polymer contains a chlorinated rubber, a poly-N-vinylpyrrolidone or a copoly (N-vinylcarbazole / methyl acrylate ( β -hydroxyethyl acrylate) and is capable of developing light-scattering centers directly which have a minimum increase in density in directed white light when measured with respect to a transparent one Provide background of 0.2 if the layer with a focused laser beam, which by the or the sic absorbable light absorbing substances is absorbed and has a radiation intensity of at least 10⁴ W cm ^-2 , is exposed to a light energy dose of at least 10 ^-1 Ws cm ^-2 , and in which this layer is not sensitive enough to such centers when exposed to the same Laser beam, but to develop a reduced intensity by a factor of 10.

Regarding the definition of "optical density in the directional Light "and its measurement is based on C. E. Kenneth Mees and T. H. James - "The Theory of the Photographic Process", The Macmillan Company, New York, 3rd edition (1969) page 421.

Under "solved" is the molecular distribution in a continuous To understand medium, in contrast to "dispersed", which refers to conglomerates of molecules in one surrounding continuous medium.

Examples of suitable for use in the materials thermoplastic polymers are:

• 1. PARLON 300 Cp (PARLON is a trademark of The Hercules Powder Company, Inc., Wilmington, Del., USA, for a chlorinated rubber). Its glass transition temperature (TG) is 96 ° C.
• 2. LUVISKOL K-90 (LUVISKOL is a trademark of BASF AG, Ludwigshafen, FRG, for a poly-N-vinyl pyrrolidone). The TG of the polymer used is 143 ° C, the molecular weight is 700,000.
• 3. Copoly (N-vinylcarbazole / methyl acrylate / β -hydroxyethyl acrylate) with a TG of 96 ° C and the following structure: with x = 60% by weight y = 30% by weight z = 10% by weight

This copolymer was made as follows:

In a 2 l reaction vessel with stirrer, cooler, two dropping funnels and nitrogen were added the following substances mixed and flowed with nitrogen:

800 ml demineralized water,
10 g HOSTAPON T (trade name of Farbwerke Hoechst AG, Frankfurt (M) -Höchst, FRG) for a wetting agent with the formula

120 g of N-vinyl carbazole.

The reaction mixture was heated on a water bath at 75 ° C. Then a mixture of 60 g of methyl acrylate and 20 g of β- hydroxyethyl acrylate was passed through a dropping funnel for 30 minutes together with 40 ml of a 2.5% strength by weight aqueous solution of 4,4′-azobis (4-cyanovaleric acid) dropped in the other dropping funnel. The temperature of the reaction mixture rose to 80 ° C and reflux occurred. The reaction mixture was kept at 80 ° C. for 20 minutes, whereupon the temperature was raised to 90 ° C. and the mixture was kept at this temperature for 3 hours. It was then stirred overnight and allowed to cool to room temperature. The precipitate formed was suction filtered and treated with a mixture of 900 ml of tetrahydrofuran, 900 ml of methanol and 900 ml of a 5% by weight sodium chloride solution. The originally soft copolymer precipitate became brittle and was separated by decanting and washed three times with water.

The TG of the copolymer obtained was 96 ° C.

The for use in the recording materials of the invention suitable thermoplastic polymers preferably have a broad molecular weight distribution.

The molecular weight distribution of a polymer can be determined by gel permeation chromatography. A polymer consists of n ₁, n ₂. . . n _i . . . n _N molecules with the corresponding molecular masses M ₁, M ₂,. . . M _i . . . M _N. The weight of all molecules with the molecular mass M _i is thus ω _i = n _i M _i . The following formula is used to define the molecular weight distribution:

With:

This formula represents the molecular mass that the polymer would have if all molecules were the same size. The average Molecular mass in ω-Weight is:

L = 1 for a monodisperse product and L is higher the more polydisperse the polymer is. The chlorinated rubber PARLON 300 Cp® is characterized by L = 10.

Organic dyes with good phototechnical stability are for use in the recording materials of the invention prefers. Examples of such dyes can can be found in the table below, behind their chemical structure or its name the color index number (C.I. number) stands.

table

Of these dyes, dye # 1 is used preferred in connection with an argon ion laser Absorption maximum very close to the laser wavelength 514.5 nm is, namely at 519 nm.

The concentrations of this (these) dyes (s) in the Recording layer is within the limits defined above and is usually in the range of 1 to 5% by weight on the polymer or polymers.

The recording layer is preferably on a carrier material applied, although self-supporting recording materials cannot be excluded. Suitable carriers are dimensionally stable supports including glass plates, metal foils, Resin films and resin plates, e.g. B. from a polyester or Polystyrene.

The thickness of the recording layer is in the range of 0.5 to 10 µm, preferably 1 to 2 µm.

The recording materials, the recording layer, as defined in the present process,  are achieved by layering a solution containing at least one suitable thermoplastic polymer and the one or more Contains dyes, made on a support on which the coating can be removed permanently or after drying is liable. Self-supporting recording layers can be produced by removing the coating from a preliminary Strips off carrier.

When writing with the laser beam, the recording materials are preserved immediately a trace of tiny light scattering Centers that correspond to the areas hit by the laser light.

The laser beam is preferably applied to the recording layer to a spot of 0.5 to 10 µm², preferably 1 to 4 µm², focused.

To achieve a satisfactorily high recording speed, i. H. To achieve laser writing speed, the recording takes place according to the present invention with a laser an output energy of preferably at least 100 mW. Such lasers include e.g. B. to the class of high-energy gas lasers. A preferred laser for use in the present Invention is the argon ion laser with a light output of 1.4 W at 514.5 nm.

An overview of lasers including ion gas lasers Light outputs on the order of watts in the visible Spectrum, Marce Eleccion gives in IEEE Spectrum, March 1972, Pages 26-40.

The intensity and deviation of laser beams can be with the help the means known to those skilled in the art can be modulated. Because the generation  and control of laser beams by devices and procedures that are not part of the present Are invention and which are known to the expert, this is not explained in detail here.

Since the image recording is based on light scattering, this can achieved patterns are used to create transparencies, whose non-transparent areas correspond to the areas, that were exposed to the laser beam. For projection purposes direct light ("specular light"), d. H. in one Narrow-angle projected light onto the one provided with an image Recording material directed. Those exposed to the laser beam Surfaces scatter this beam of light, while in the unexposed areas let light pass through unchanged becomes. In this embodiment, the recording layer stacked on a transparent support.

A photograph with the reverse of this transparency Image values can be obtained by using the recording layer or coating on a black background, e.g. B. an opaque support or one coated with a black layer Carrier, places and light on the exposed to the laser beam Layer judges. In the black background all reflected light passing through the recording layer absorbed; in the areas exposed to the laser beam however some of the light is scattered forward. Therefore come in this embodiment, those exposed to the laser beam Areas bright against a dark background for illustration and one consequently receives the in comparison with transmission exposures inverse effect.

The following examples illustrate the present invention. All ratios and percentages relate if not otherwise stated, on weight.  

example 1

20 mg of dye No. 4 of the table were in 10 ml of a 10% Solution of the thermoplastic polymer defined above PARLON 300 Cp® in 1,1,2-trichloroethane solved.

2 ml of the solution obtained was poured onto a glass plate, which is fixed on a turntable rotating at 1000 rpm was. The glass plate had a thickness of 1.7 mm and measured 5 cm × 5 cm. The coating obtained was dried at 25 ° C.

The dried recording material had an optical density in the directional light of 0.37 at 514.5 nm, measured with a UNICAM® Sp 1800 UV spectrophotometer.

The recording layer was placed on a turntable one of an argon ion laser with an output power of 1.4 watts at 514.5 nm emitted laser beam exposed to this wavelength. With the help of optics, the laser beam was focused on a Focused area of 4 µm². The recording was done by using the laser beam on the recording layer wrote a spiral line. The recording started on the Periphery of the glass plate while moving the beam inwards to the center while the turntable at an angular velocity was rotated from 2000 rpm.

The recording material on the turntable was inclined from 0.3 ° to the optical axis of the exposure system, so that when turning the disc always a certain area of the the focus of the writing line.  

The exposure technique is illustrated in Fig. 1, which shows the schematic view of the device used. The laser 1 generates a laser beam 2 therein, which is focused with a lens 3 . Element 4 represents a semi-transparent mirror (beam splitter), with the help of which the focusing can be checked. A mirror 5 directs the laser beam through an aperture 6 into the microscope objective 7 . Through this lens 7 , the focused laser beam hits the recording material 8 , which is placed on a turntable 9 , driven by an electric motor 10 . The axis of the turntable forms a small angle (0.3 °) with the optical axis of the beam, so that the beam will always be in focus in part of the spiral line. The spiral line is obtained by moving the optical device 11 , which contains the mirror 5 , sideways with the aid of the drive device 12 .

In the focal spot, the radiation intensity of the incident laser beam was 1.25 × 10⁷ W cm ^-2 . The absorbed radiation dose was 12 Ws cm ^-2 .

A light-scattering track was obtained in which the line width was between 1 and 2 µm and the optical density in directed white light, measured with the automatic ANSCO® Model 4 Recording Microdensitometer under the conditions already described, was over 0.5 inherent veil.

Example 2

Example 1 was repeated, except that the dye No. 4 replaced by 50 mg of dye No. 9 in the table has been.

The recording material had an optical density in the directional Light of 0.87 at 514.7 nm.  

The laser beam recording went according to the description in Example 1 in front of you.

A light-scattering track with a density in the directional was obtained white light of 0.5 over inherent veil.

Example 3

50 mg of dye No. 9 of the table were in 10 ml of a 6% solution of the copoly (N-vinylcarbazole / methyl acrylate / hydroxyethyl acrylate) already mentioned (60/30/10) dissolved in 1,1,2-trichloroethane.

The coating was carried out as in Example 1. Die Recording layer was dried at 25 ° C. The dried one Recording material had an optical density from 0.69 at 514.5 nm.

The recording was carried out as in Example 1, but with the difference that the laser beam recording was carried out at 1000 rpm. The received light dose was 24 Ws cm ^-2 , the intensity of the laser beam being the same as in Example 1, namely 1.25 × 10⁷ W cm ^-2 .

A light-scattering track with a density in the directional was obtained white light of 0.5 over veil.

Example 4

50 mg of dye No. 3 in the table were in 10 ml of a 10% solution of the poly-N-vinylpyrrolidone described above dissolved in non-anhydrous ethanol.  

The coating was carried out as in Example 1. The recording layer was dried at 25 ° C. It had an optical one Directional light density from 0.4 to 476 nm.

The recording layer was exposed as described in Example 1, but with the difference that a laser beam of 476 nm with an energy of 100 mW was used and that the turntable rotated at 1200 rpm. The light dose received by the recording layer was 2 Ws cm ^-2 , the radiation intensity was 1.25 × 10⁶ W cm ^-2 .

A light-scattering track with a density in the directional was obtained white light of 0.5 over inherent veil.

Example 5

The exposure of a manufactured according to the following description colored latex was as in Example 1. The recording layer was dried at 25 ° C. The dried one Recording material had an optical density in the directional Light of 0.2 at 514.5 nm.

The laser recording was carried out as in Example 1, but with the difference that the turntable rotated at only 500 rpm, so that the exposure dose was 50 Ws cm ^-2 .

A light-scattering trace was obtained as in the previous ones Examples.

Production of the colored latex

25 g of Rouge Feu Savinyl 3 GLS (C.I. Solvent Red 124) were added to one Mixture of 200 g of ethyl acrylate and 50 g of methyl methacrylate added. Undissolved dye was removed by filtration  and the further amounts were added to the dye solution obtained of 200 g of ethyl acrylate and 50 g of methyl methacrylate. The The mixture obtained was called mixture A.

250 ml of a 2% by weight solution of potassium persulfate in water were made and called Mixture B.

A solution of 575 ml of water and 250 ml of a 10 wt .-% Solution of sodium oleyl methyl tauride was heated to 72 ° C.

1/4 of mixture A was added to this solution at once Stir was added and the temperature was allowed to drop to 70 ° C. Then 1/4 of the mixture B was added. The temperature rose to 73 ° C in 5 min. Then 3/4 of A and 2/4 of B gradually added over 25 min. The temperature reached 90 ° C. The remaining was 95 minutes after the addition of this portion 1/4 of mixture B was added and stirring continued for 2 h while the temperature was kept at 90 ° C. The polymerization was completed at 95 ° C within a further 30 min.

Example 6

50 mg of dye No. 6 of the table were in 10 ml of solution of the above-described poly-N-vinylpyrrolidone in ethanol from 4% water content dissolved. This solution had a polymer concentration which corresponded to a viscosity of 50 mPa · s at 20 ° C.

The coating was carried out as in Example 1. The recording layer was dried at 25 ° C.

The dried recording layer had an optical density in the directional light of 0.1 at 488 nm.  

The laser beam recording was carried out as described in Example 1, with the difference that laser light of 488 nm was used. The light dose applied was 12 Ws cm ^-2 .

The radiation intensity was 1.25 × 10⁷ W cm ^-2 . The recording with the laser took place at 2000 rpm of the turntable.

A light-scattering track with an optical density was obtained in directed white light of 0.5 over inherent veil.

Example 7

50 mg of pigment No. 8 of the table were in 10 ml 10% solution of the chlorinated rubber described above in 1,1,2-trichloroethane, which have a viscosity of 46 mPa · s at 20 ° C, dissolved.

Coating and drying were carried out as in Example 1.

The dried recording layer had an optical one Directional density of 0.30 at 514.5 nm.

The laser recording was carried out as described in Example 1, but with the difference that the turntable at 1000 rpm rotated.

The light dose applied was 24 Ws cm ^-2 . The radiation intensity was as described in Example 1.

A light-scattering trace was obtained as in Example 1.  

In connection with the above examples must be noted be that while reducing the laser radiation intensity no light-scattering trace by a factor of 10 in each example more was achieved.

Example 8

25 mg of dye No. 1 in the table were 10% in 10 ml Solution of the chlorinated used in the previous example Rubber dissolved in 1,1,2-trichloroethane. The received Solution was applied with a wet layer thickness of 0.05 mm a black bismuth layer with a polyethylene terephalate film applied as a carrier. The description received was dried at 25 ° C.

The bismuth layer was reduced by vapor deposition Pressure was applied to the 0.1 mm thick polyethylene terephthalate film. It had a thickness of 15.0 nm and an optical one Density above 4.

After the laser beam exposure, as described in Example 1, the differentiation of light reflection achieved between the surfaces exposed to the laser beam (the spiral line) and the non-laser exposed areas with directed light with the help of the ANSCO® microdensitometer measured a numerical aperture of 0.4.

In the background areas the optical density was Reflection 1.5 and in the areas of the spiral track in one width of 3.5 µm, it was only 0.5.

Claims (11)

1. Recording material for the direct generation of a light-scattering image which contains at least one thermoplastic polymer layer with at least one dye, characterized in that the dye has good photochemical stability, the dye of the layer has an optical density in directional light of at least 0.1, based to a monochromatic wave of a laser beam absorbed by the substance (s), the dye is present in an amount of at most 10% by weight, based on the thermoplastic polymer (s) of this layer, and that the polymer layer contains as a thermoplastic polymer a chlorinated rubber, a poly-N-vinylpyrrolidone or a copoly (N-vinylcarbazole / methyl acrylate ( β -hydroxyethyl acrylate) and is capable of direct development of light-scattering centers which have a minimum increase in density in directional white light when measuring with a transparent background of 0.2 if the Layer with a focused laser beam, which is absorbed by the visible light-absorbing substance or substances and has a radiation intensity of at least 10 cm W cm ^-2 , a light energy dose of at least 10 ^-1 Ws cm ^-2 , and that this layer is not sensitive enough is to develop such centers when exposed to the same laser beam, but by a factor of 10 reduced intensity. 2. Material according to claim 1, characterized in that the visible light absorbing material is an organic one Dye is. 3. Material according to claim 1 or 2, characterized in that the thermoplastic polymer is a chlorinated Rubber with a glass transition temperature of Is 96 ° C. 4. Material according to claim 1, characterized in that the thermoplastic polymer is a poly-N-vinyl pyrrolidone with a glass transition temperature of 143 ° C. 5. Material according to claim 1, characterized in that the thermoplastic polymer has the following structural formula with x = 60% by weight y = 30% by weight z = 10% by weight and a glass transition temperature of 96 ° C. 6. Material according to any one of claims 1 to 5, characterized characterized in that the polymer layer one or several dyes in a concentration in the range from 1 to 5% by weight, based on the polymer or polymers, contains. 7. Material according to at least one of claims 1 to 6, characterized in that the layer of one transparent or opaque straps. 8. Material according to at least one of claims 1 to 7, characterized in that the layer has a thickness in the range of 0.5 to 10 µm. 9. Process for direct generation of a light scattering Image in at least one thermoplastic Polymer-containing recording layer by means of a laser beam, characterized in that one a recording material according to at least one of the Claims 1-8 used. 10. The method according to claim 9, characterized in that the laser beam is on the recording layer a spot of 0.5 to 10 µm² is focused. 11. The method according to any one of the preceding claims, characterized in that the laser beam from a Argon-ion laser with a light output at 514.5 nm is produced.